C＃中的起始点表示法是什么？

Question

I came across a tutorial on Full Stack .Net Web Development and I've never seen the use of the dot operator is this way for C# as of yet. Can someone explain what it means in regards to why don't the statements end in semicolons and also do the statements belong to a specific object?

using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;

namespace MyApi
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()
                .UseStartup<Startup>()
                .Build();

            host.Run();
        }
    }
}

Answer 1

It is simply a single statement split across multiple lines, and also an example of fluent method chaining.

Each method call returns an object, which then can be de-referenced to perform another method call.

Here's a simple-ish example to give you an idea of how it works. Note how each method returns the current instance of Person , ie this .

class Person
{
    public string Firstname { get; set; }
    public string Surname { get; set; }
    public DateTime DateOfBirth { get; set; }
    public decimal HeightCm { get; set; }

    public Person WithName(string firstname, string surname)
    {
        Firstname = firstname;
        Surname = surname;
        return this;
    }

    public Person BornOn(DateTime date)
    {
        DateOfBirth = date;
        return this;
    }

    public Person WithHeight(decimal heightCm)
    {
        HeightCm = heightCm;        
        return this;
    }
}

You can then do the following:

var person = new Person().WithName("Doctor", "Jones").BornOn(new DateTime(1980, 1, 1)).WithHeight(175);

Which can also be expressed as:

var person = new Person()
    .WithName("Doctor", "Jones")
    .BornOn(new DateTime(1980, 1, 1))
    .WithHeight(175);

Splitting it across multiple lines is not necessary, but could either be a stylistic choice, or dictated by your coding standards.